Add UnpooledUnsafeDirectByteBuf and use it when low-level access is a…

…vailable

- Remove PooledUnsafeDirectByteBuf.setMedium() which is redundant
- Fix constructor visibility

buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java

@@ -585,10 +585,10 @@ public ByteBuf setZero(int index, int length) {
 
     @Override
     public byte readByte() {
-        if (readerIndex == writerIndex) {
-            throw new IndexOutOfBoundsException("readerIndex(" + readerIndex + ") == writerIndex(" + writerIndex + ')');
-        }
-        return _getByte(readerIndex++);
+        int i = readerIndex;
+        byte b = getByte(i);
+        readerIndex = i + 1;
+        return b;
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java

@@ -163,13 +163,6 @@ protected void _setShort(int index, int value) {
         PlatformDependent.putShort(addr(index), NATIVE_ORDER ? (short) value : Short.reverseBytes((short) value));
     }
 
-    @Override
-    public ByteBuf setMedium(int index, int value) {
-        checkIndex(index, 3);
-        _setMedium(index, value);
-        return this;
-    }
-
     @Override
     protected void _setMedium(int index, int value) {
         long addr = addr(index);

buffer/src/main/java/io/netty/buffer/Unpooled.java

@@ -15,6 +15,8 @@
  */
 package io.netty.buffer;
 
+import io.netty.util.internal.PlatformDependent;
+
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.CharBuffer;
@@ -206,6 +208,8 @@ public static ByteBuf wrappedBuffer(ByteBuffer buffer) {
                     buffer.array(),
                     buffer.arrayOffset() + buffer.position(),
                     buffer.remaining()).order(buffer.order());
+        } else if (PlatformDependent.hasUnsafe()) {
+            return new UnpooledUnsafeDirectByteBuf(ALLOC, buffer, buffer.remaining());
         } else {
             return new UnpooledDirectByteBuf(ALLOC, buffer, buffer.remaining());
         }

buffer/src/main/java/io/netty/buffer/UnpooledByteBufAllocator.java

@@ -36,6 +36,10 @@ protected ByteBuf newHeapBuffer(int initialCapacity, int maxCapacity) {
 
     @Override
     protected ByteBuf newDirectBuffer(int initialCapacity, int maxCapacity) {
-        return new UnpooledDirectByteBuf(this, initialCapacity, maxCapacity);
+        if (PlatformDependent.hasUnsafe()) {
+            return new UnpooledUnsafeDirectByteBuf(this, initialCapacity, maxCapacity);
+        } else {
+            return new UnpooledDirectByteBuf(this, initialCapacity, maxCapacity);
+        }
     }
 }

buffer/src/main/java/io/netty/buffer/UnpooledDirectByteBuf.java

@@ -51,7 +51,7 @@ final class UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {
      * @param initialCapacity the initial capacity of the underlying direct buffer
      * @param maxCapacity     the maximum capacity of the underlying direct buffer
      */
-    public UnpooledDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
+    UnpooledDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
         super(maxCapacity);
         if (alloc == null) {
             throw new NullPointerException("alloc");
@@ -76,7 +76,7 @@ public UnpooledDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int ma
      *
      * @param maxCapacity the maximum capacity of the underlying direct buffer
      */
-    public UnpooledDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity) {
+    UnpooledDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity) {
         super(maxCapacity);
         if (alloc == null) {
             throw new NullPointerException("alloc");